'02 Sierra P0440

[crazy4offroad]

Like the title says, code P0440, "Evaporative Control System Malfunction". When sitting still idling I can open the driver's door and smell gas strong. Strike 1 = gas cap is an aftermarket locking style. Took off the charcoal box by the tank, shook it, checked the lines, all seems OK with it but that doesn't really mean anything. Checked for voltage at the (purge?) valve on the engine, which it had but didn't verify the operation of the valve. Is there a common failure part that I should check first or just quit being lazy about it and start actually testing things?

 

[Jims86]

I would say stick an OEM cap back on, clear it, and see if it comes up again. I have heard of lines in the system being plugged...maybe disconnect and blow a little air through. is there a two wire plug at the EVAP solenoid...a pink wire, and a white wire I think? You can turn the key on, and use a probe to ground the white wire to see if the solenoid clicks...if it does, that means your not spending $345 for a new solenoid....i think GM parts Direct has them for MUCH cheaper...like $80.

 

[crazy4offroad]

Thanks, I'll check the solenoid in the morning. It's on the engine right? I need to get the book out anyway.

 

[crazy4offroad]

And since it wouldn't let me "give it to you" that way I'll have to do it this way, but it's the thought that counts, right?!

 

[Jims86]

And since it wouldn't let me "give it to you" that way I'll have to do it this way, but it's the thought that counts, right?!

LOL! Right on. I THINK the solenoid for the LS evap systems are back on the cannister.

 

[Jims86]

its on the frame, near the cannister...#2

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[bucket]

Yup, I've had to replace that vent solenoid on a few trucks. The purge solenoid is the one that lets the fumes get sucked into the intake.

 

[crazy4offroad]

Thanks guys, fortunately this is something that doesn't affect how it runs so I have been able to put it off, figured since we'll be in the 80s this week I should finally fix it.

 

[crazy4offroad]

Update:
Went out yesterday to start checking this thing over, checked the purge valve, it clicks so that's a good sign. Went to check the gas cap and it was loose...hmmm. I know I tighten that thing every time I fill up? It's a locking cap, think the vent valve in it is bad and the pressure made it loosen? Possible someone tried unsuccessfully to steal my gas?

At any rate, I went to the parts store and got a new NON-LOCKING gas cap (you'll have to PM me to see my unlisted video of why no one should waste money on those useless things), and a package of 16 awg wire, 18' roll and a door jamb/dome light switch. Swapped out the cap, cleared the code, then installed the door switch inside the door jamb of my gas door. Fished the wire to the cab and spliced it to the driver door trigger wire (tan wire in the purple cluster under the column). Now when the alarm is armed and someone opens my gas door the alarm goes off. I'll have to post back in a week or so to let you guys know if the gas cap fixed the problem, I'm hoping it did. And by the way 10' or so would have been plenty but I use a lot of wire for other projects, may tie the tailgate into the alarm the same way.

 

[bucket]

That's a really good idea! So when you open the gas door, does the dome light come on?

And yeah, anyone with a brain can remove a locking gas cap. BUT, lots of thieves don't seem to have a brain.

 

[crazy4offroad]

I only tested it in daylight so I'm not sure if the dome light comes on. The "trigger" wire I think is more for the alarm which might make the dome light come on. I'm pretty sure the headlights and tail lights flash, and horn blows off/on/off. Pretty sure power is cut to starter, fuel pump and ignition as well. I was shocked how easy it is to remove a locking gas cap, even without a pick or similar key. They're completely worthless.

And anyone looking to do a similar wiring job may want to look at this page, they have a tremendous collection of wiring diagrams for hooking up or tying into car alarms...
http://alarmsellout.com/pages.php?pageid=25

 

[Jims86]

You should be able to tell in the next 40 or so miles whether or not the new cap works. Great idea on the fuel door trigger for the alarm!

 

[crazy4offroad]

Also you want the switch close to the hinge. I had one wire up in the silver Tacoma tailgate jamb near the middle and slamming the tailgate junked it. If it would have been towards the bottom near the pivot point of the tailgate it wouldn't have gotten beat up so bad. I had put a power tailgate lock on it as well so I wasn't quite as worried about it.